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Posted: 9/28/2011 5:52:17 PM EDT
OK I'm really getting frustrated right now. For the last 3 days now my truck won't run worth a damn. I replaced the plugs which were all fouled up along with the wires. I should mention the truck has under 70k miles (69 and change) the computer codes were gone through and both O2 sensors triggered a code. I just replaced them with BOSCH's. I double checked all the fuses and everything was good in there and thought while I was in there I would replace the O2 sensor relay just in case. I started her back up again and still idle's and runs rough. SO rough it drives like it has a misfire (very audible) All the plug wires are correct and still no resolution to the problem. I am usually pretty good with cars,but this is killing me. Electrical gremlins drive me nuts. Currently the check eng. light is out with no codes present. My next step was to chk the cap and rotor, but don't want to arbitrarily start replacing parts that don't need to be.
Please someone help me out.
Link Posted: 9/28/2011 6:01:02 PM EDT
Let me guess. Code P0174 and P0171? O2 sensors were fine, check for a vacuum leak.
Link Posted: 9/28/2011 7:49:42 PM EDT
Can you explain when this happens?

Does it misfire all the time - or just a few minutes after startup?

Does the misfire clear up if you put it in neutral and rev it up a bit?

Link Posted: 9/29/2011 2:31:49 AM EDT
[Last Edit: 9/29/2011 2:32:53 AM EDT by P400]
Check the basics first. The ignition system is a good place to start. How do your plugs look?
Link Posted: 9/29/2011 3:11:35 AM EDT
with wires, I assume a 3.9/5.2?
Link Posted: 9/29/2011 5:38:36 AM EDT
[Last Edit: 9/29/2011 5:39:34 AM EDT by Medic-1]
The misfire is almost constant drives like it has no power at all. The 2 codes that showed up for the O2 sensor were PO031 and PO037. Sensor 1/1 heater circuit low and Sensor 1/2heater circuit low.Also it's the 3.9l V6.
Link Posted: 9/29/2011 5:45:38 AM EDT
I have 2000 V8 Dakota that seems to have Throttle Position Sensor issues about every 6 months. I have to have it cleaned at every oil change now and it still acts up sometimes.

Pulled this off a Dakota site...not sure if these are your exact symptoms:

RE: bad tps symptoms
IP: Logged

My bad TPS symptoms were;

-unstable idle, from 400 up to over 1000

-sporadic converter lockup during constant hwy speed, rpm would jump 200 up and down, every few seconds

-erratic transmission shifts in city driving, sometimes quite hard

-occasional stall when coming to a stop or shifting to 'drive' or 'park'

These bugs all disappeared with a new TPS, and as a bonus; my fuel mileage improved by a point or two ...that will quickly cover the cost of the new part. A defective TPS will often NOT give an engine code, unless it exceeds its voltage range,
and by then your engine probably isn't running anyway.

A bad IAC will cause unstable idle, difficult starting, and stalling.

Link Posted: 9/29/2011 5:48:57 AM EDT
EGR valve?

Link Posted: 9/29/2011 6:36:22 AM EDT
Before I erased the codes the following ones popped up
Poo31 1/1 low htr circuit
poo37 o2 htr circuit low
po132 1/1 o2 volt too high
po133 o2 1/1 slow response
po300 multiple cyl misfire
po302 #2 misfire
po304 #4 misfire
po138 unknown

Once these were erased only OO31 and OO37 remained checked the fuse panel cleared the codes once again and now no codes remain.....
Link Posted: 9/29/2011 6:48:27 AM EDT
Originally Posted By Medic-1:
The misfire is almost constant drives like it has no power at all. The 2 codes that showed up for the O2 sensor were PO031 and PO037. Sensor 1/1 heater circuit low and Sensor 1/2heater circuit low.Also it's the 3.9l V6.

Ah well, never mind then.
Link Posted: 9/29/2011 6:55:56 AM EDT
Since this is happening all the time, I would start at the below link and make sure your plug wires are routed correctly.



After doing that - I would recommend removing the Bosch o2 sensors, and replacing them with Denso, the OEM brand. I (and others) had significant driveability issues with non-oem o2 sensors. They are about ~$40/ea from Rock Auto (PM me if you want a discount code for 5-pct - I am not affiliated with them, just passing along information).

FWIW - here is the tread I started over at Dakota-Durango.com which details my problems (I also have a 3.9 V6 Dakota).


Also check he vacuum line that goes from the MAP sensor to the throttle body - it is actually a rubber elbow that seems to like to crack, so it looks fine at first glance - but a closer look reveals the crack.
Link Posted: 9/29/2011 7:55:04 PM EDT
lots of great info on that forum.I will have to look at some of those areas to see if anything fixes it.
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